Conventionally, an information input/output method for reading a barcode printed on a printed material and the like and outputting information such as a sound, an image, and a motion picture is proposed. For example, there has been proposed a method for storing information that matches with key information that is given in advance in the storage unit and outputting information and the like by searching from a key read out by a barcode reader. Also, there has been proposed a method for generating a dot pattern in which fine dots are arranged according to a predetermined rule in order to output a lot of information and programs, retrieving the dot pattern printed on a printed material and the like as image data using a camera, analyzing the dot pattern and converting the dot pattern into a dot code, and outputting content data such as a sound registered by being associated with the dot code in a link table. (WO2004/084125, WO2004/029871)